Invalid walkers are highly useful devices for assisting physically handicapped persons to walk.
A conventional invalid walker is essentially an open, lightweight frame fitted with four adjustable, rubber-tipped legs. In use, a handicapped person leans on the walker for support between steps. In moving forward, he physically lifts the walker and advances it to a new position where it again provides support. The major difficulty with this type of walker is that it fails to provide support during stepping, when it is needed most. In addition, the user must burden his injured legs with both his own weight and that of the walker.
Attempts have been made to overcome these difficulties by applying rollers to the walker. Such walkers have typically been provided with frictional brakes to be applied at the discretion of the user. These walkers, however, have generally been unsafe because the walker's movements are completely uncontrolled until the user applies the brakes. Unless the handicapped user has agility, alertness and strength, comparable to that of a driver of an automobile, there is a serious possibility that the walker will roll ahead of him to such a degree that it can no longer provide vertical support.
To reduce the risk of uncontrolled rolling, U.S. Pat. No. 4,018,440, issued to applicant Fritz A. Deutsch, discloses a rolling walker having an incrementing wheel control mechanism which permits a wheel to roll a predetermined distance corresponding to a step and then automatically locks it. The handicapped person releases the wheel and then steps forward. The walker rolls forward with the step, providing support and then locks. The user thus moves forward in a series of releases, steps and locks. While this incrementing walker is a distinct improvement over the conventional walker, the necessity of successive releases between steps, like the necessity of lifting a conventional walker, makes it difficult for the user to practice a "normal" smooth gate.
Accordingly, there is a need for an improved rolling walker capable of permitting safe, continuous walking at a normal gait.
In an effort to provide a rolling walker for permitting the user to engage in continuous walking, applicant Deutsch devised a Bowden cable controlled walker having normally locked wheels. This walker is described in the Bulletin of Prosthetics Research, pages 182-184, U.S. Veteran's Administration (BPR 10-31 Spring 1979). A single handgrip coupled to the locking mechanisms via the cable permitted the user to disengage the locking mechanism enabling the walker to roll.
This cable controlled walker, however, presents a number of problems. One is that the cable is a relatively frictional coupling, and many handicapped users find it difficult and tiresome to exert the grip pressure required to enable the walker. A second difficulty is that cable coupling is relatively flimsy. Connections can easily be broken if, for example, the cable snags on a solid object. Furthermore, even in the absence of disconnection, the cable arrangements must be adjusted at a relatively high frequency. Moreover, the usefulness of the walker in accommodating users with different hand preferences (i.e. right or left) is limited by the substantial difficulty in switching the grip and cable coupling from one side of the walker to the other.